Our society has come to rely on batteries to power a myriad of devices, including computers, cell phones, portable music players, lighting devices, as well as many other electronic components. Nevertheless, there is an ongoing need for further advances in battery technology. For example, there is still a significant need for economical batteries that can power automobiles or provide load-leveling capabilities for wind, solar or other energy technologies. Furthermore, the “information age” increasingly demands portable energy sources that provide lighter weight, higher energy, longer discharge times, more “cycles,” and smaller customized designs. To achieve these advances, technologists continue to work to develop batteries with higher and higher energy densities while still providing acceptable safety, power densities, cost, and other needed characteristics.
U.S. Pat. No. 8,012,621, which was filed by Joshi, et. al., is an example of battery technology that is currently being researched. (As noted above, this U.S. patent is expressly incorporated herein by reference.) U.S. Pat. No. 8,012,621 describes a battery cell where a metal hydride is the negative electrode and a nickel hydroxy-oxide electrode is the positive electrode. In both positive and negative electrode chambers, there is an alkaline electrolyte comprised of alkali metal hydroxide dissolved in a water solvent. The patent discloses a substantially nonporous alkali metal ion conductive ceramic membrane to separate the electrode compartments. In this patent, “substantially nonporous” means that at least a portion of the cross-section of the membrane has little or no through porosity such that transport across the membrane primarily must occur through the membrane lattice structure and channels rather than through pores. During operation of the cell described in this patent, an alkali cation carries the charge during charging/re-charging of the battery (rather than the hydroxyl ion that is used as part of the reaction at the electrode). Advantages of this system include a prevention of undesirable species migration from one electrode to another. This patent may also result in improved columbic efficiency as well as negligible self-discharge between cycles and during storage.
Additionally, U.S. patent application Ser. No. 12/022,381 represents another type of battery technology. (This patent application has been published as U.S. Patent Application Publication No. 2009/0189567, and as noted above, this patent application has been expressly incorporated herein by reference.) In U.S. patent application Ser. No. 12/022,381, a battery cell is described in which a zinc negative electrode is utilized with a multitude of different positive electrode materials (such as, for example, MnO2, AgO or Ag2O, NiOOH, O2, HgO, CdO, Cu2O). In all these cases, an alkaline electrolyte is utilized on both sides of the cell, and this alkaline electrolyte is understood to be a water-based material. This system provides the advantage of having a non-porous membrane separating anode and cathode, resulting in high columbic efficiency and a prevention of self discharge.
At the same time, the above-recited patent documents all utilize an aqueous (alkaline) electrolyte. However, there are candidate negative and positive electrode materials that are not compatible with aqueous electrolytes. These aqueous-incompatible electrode materials offer advantages in terms of cyclability, energy density and cost per energy unit. For example, magnesium is a relatively low cost and energy dense electrode material with a very negative reduction potential (relative to hydrogen). In fact, use of a magnesium electrode can result in a very low cost per energy unit when coupled with many candidate electrodes with higher reduction potentials. However, magnesium is not compatible with water since it reacts with water. Aluminum is another low cost electrode material candidate material with similar advantages to magnesium but also is not compatible with an alkaline, water-based electrolyte. Thus, magnesium and aluminum cannot be used as the electrode material in the above-recited systems.
Accordingly, there is a need in the industry for a new type of battery that does not require an aqueous electrolyte and can use materials, such as magnesium and aluminum, as the electrode material. Such a device is disclosed herein.